Density responsive device



Jan. 2, 1940. G. BEARDSLEY, JR., ET Al.

DENS ITY RESPONS IVE DEVICE Filed'nec. so, 1956 wfwj// /Y/ST l 1 1N VEN TOR. IyEBerds Patented Jan. '2,1940

l UNITED STATES 2,185,518 DENSITY' aEsroNsIvE DEVICE Guy E. -Beardsley, Jr.; West Hartford,l and John S. Hasbrouck; Manchester, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., incorporationI of Delaware Application December 30, 1936, Serial No. 118,314

22 Claims.

This invention relates to improvements in air density responsive devices, and has for an object the provision'of a device which is accurately responsive to changes in airdensity over a`wide I range of density variation.

. A further object resides in the provision of a device of the character Vdescribed which has a' movable portion which changes its position in response to changes in` air density and which movable l0 portion may be used to operate afdensity indicating means or to control another device which is affected by changesin air density.

A still further object resides in the provision of adevice of the character described which is capable of exerting a force suiicient to change the setting of a densityv indicating device o'r of an instrumentality which is affected by changes in air density.

other, objects and'aavantages win be more particularly pointedfouthereinafter or will become apparent as the description proceeds.

In the accompanying drawing 'in which like reference numerals are used to designate similar parts throughout, thereis illustrated -a suitablel mechanical arrangement of what, is now considered to be the preferred forni 'of the idea of the invention, together with three .exempliflcatlons' ofthe application of the device to practical puril poses.. The drawing, however, la for the purpose of illustration only and is not to be taken as limiting the invention the,scope of which is to be measured entirely by the scope of the` I' appended claims.

- In the accompanying-drawing, Fig. 1 is a verconstructei\according to the idea of this in venl tion;

' Fig. 2 is axplartly schematic sectional view of a Y carburetor fo an internal 'combustion engine showing the application of the density responsive device to the carburetor to control the fuel-air ratio of the combustible mixture supplied by the carburetor;

' Fig. 3 is a partly schematic view 'showing'the Referring to the drawing in detail, the numeral I8 generally indicates a boxlike casing in whichv the density responsive mechanism is mounted. The casing vis provided vwith side walls l2 which tical sectional view of a de'nsity responsive 'deviceI may inclose a compartment of square, cylindrical,

orother suitable form. One end of the casing is closed by a removable end ,closure member i4,

and the other end Dis closed by an end closure member I6 which, if desired, may be formed integrally 4witl the wide walls I2. Suitable holes or apertures I8 'are provided in the side walls l2 to render the interior of the casing I0 subject to the pressure and temperature of the surrounding air.

An expansible metal bellows 28 is rmly secured to the end wall i4 by a suitable anchoring means 22 and is illed with a suitable gas, such as air, at a predetermined pressure which may be selected in view of the purpose for which the density responsive device is to be used. As the presentinventioncontemplates the use of the density responsive device on an airplane in which case it would be responsive to air densities at and below the density of the atmosphere at sea level, the pressure of the gas in the bellows 2D isdesignedto be slightly above the pressure of the:

atmosphere at sea level. The end ofthe bellows 20 opposite the mounting 22 is relatively free to move, but movement in a direction to expand.

the bellows is opposed by a coiled compression lspring 24 disposed between'the free end of the bellows and a movable abutment 26 carried upon the inner end of a reciprocable shaft 28. The

shaft 28. passes through a bearing aperture 3l) in the end wall i6 of the casing I0 and carries upon its outer end a piston 32 reciprocable in a' cylinder 34 carried upon or formed integrally with the end wall I6. 1'1he outer end of the cylinder is closed by a suitable plug or closure member 36. From the above description, it will be observed that compression of the spring 24 opposes outward movement of the freeend of the bellows 28 incident to'an expansion oi the bellows and ,that movement of the abutment 26 by the piston 32 is effective to change the loading of the spring end, as indicated at 44, upon the upper or inner.

end of an aperturedlug 46 formed upon or secured to the inner side of the sidewall l0. 'The lever member 42 has an extension 48 extending beyond the connection of the lever with the bearingportion 38, the free end of the lever` being connected to a valve rod by suitable means,

' by means of a cylindrical insert or bushing 62 disposed in the cylindrical extension t0.

The valve rod is provided with annular valve portions Gd and 66 separated from each other and from the end portions of the valve rod by annular reduced portions 68, ld, and l2.

The cylindrical extension t@ is provided upon one side thereof with ports 7d, 1t, and 'is which lead into the valve aperture 58 in a direction transverse to the axis of the aperture and which are connected at the exterior of the cylindrical extension with uid conduits 00, 82, and d, respectively. Upon the opposite side of the cylindrical extension from the ports 16, l, and l@ are provided ports 86 and 83 which lead from the valve aperture 58 to the interior of the cylinder 3i, the port 86 being disposed approximately midway between the port le and 7S andthe port t8 being disposed approximately midway between 'the ports 'it and l0. Fluid under pressure is led through the conduit 82, and the conduits 8d and 8d lead from the valve aperture to drain. The piston 32 is normally disposed between the cylinder ends of the ports 86 and 8d.

From the construction so far described, it wil be observed that if the bellows 2B tends to expand in response to a decrease in the density of the surrounding atmospher it will move the valve stem 50 to the right as viewed in Fig. 1, thereby causing a movement of the valve portion 68 which connects the portv'lt with the port 00 to supply uid under pressure to the right-hand end of the piston 32, at the same time causing move ment of the valve portion t@ which connects the yport 1,4 with the port B6 and relieves the pressure When the bellows has been brought to a position in which the valve portions 64 and 66 close the ports 06 'and 08 andthe piston is retained in its new position.

A shaft 9 0 is connected to the shaft 28 by suitable means, such as the,crosshead 92 so that it follows the axial movements of the shaft 28. Thus, whenever the piston 32 moves the shaft 28 to a new position to compensate for a change in the density of the atmosphere surrounding the bellows 20, they shaft 90 will also Vbe moved to a different position, and the movement of the shaft 90 may be utilized for various purposes, certain examples of which will be explained hereinafter.

The crosshead 92 extends beyond its connection with the shaft 90 and is provided with an vaver-- tured end portion 94 which receives one en `d of a bi-metallic thermostatic strip 90. The Vstrip 96 is of a nature well known in the art of temperature responsive mechanisms and tends to bend with a certain force upon predetermined changes in its temperature. The end of the strip 96 opposite the end clamped 'in the crosshead 92 carries a pin or roller 98 movable in a slot |00v provided in an extension |02 provided upon the lower end of the lever 42 adjacentto theY pivot 44. The extension |02 and slot |00 extend in a direction substantially at right angles to the reaieasvs maining portion of the lever 42 and away from the crosshead 92.

From the above description, it will be observed that the bending force of the thermostatic strip 96 will be imposed upon thellever depending upon whether the temperature to which the thermostatic strip is exposed is above or below a predetermined temperature for which the devicelis adjusted.

When the piston 32 is in the position illustrated in Fig.' l, which position corresponds to the normal pressure of the atmosphere at sea level, thel roller or pin 98 is disposed substantially immediately below the pivot 44 so that the thermostat has no material eect upon the operation of the device. This arrangement is provided for the reason that whenever the density of the surrounding atmosphere is substantially the same as the density of the fluid within the bellows no correction for temperature variations is neces- `sary. As the external density diers from the internal density correction for temperature varlation becomes necessary, the amount of necessary correction being proportional to the difference in density within and outside of 'the bellows, with the arrangement illustrated or an equivalent arrangement, the corrective force of the thermostat is applied with increasing eilect as the crosshead 92 is moved inwardly by the piston 32.

One possible application of thedensity responsive device described above is schematically illustrated in Fig. 2 in which the end of the shaft 90 is connected to one end of a lever |04 which is mounted intermediate its length upon a xed pivot |06 and connected at its other end to a valve member |08 axially movable in an aperture H0 provided in a carburetor ||2 tocontrol a plurality of fuel metering jets ||4. According t0 the arrangement illustrated, the valve member |00 will be moved axially of itself upon' movement of the shaft 90 to reduce the number ofv fuel metering jets as the density of the atmos phere decreases to thereby maintain a substantially constant air-fuel ratio in the combustible mixture supplied by the carburetor.

In the application of the'device illustrated in Fig. 3, theouter end of the shaft 90- is operatively connected with a dial |||i with which a hand ||8 cooperates. The hand I8 is operated by a device responsive to atmospheric 'conditions such as an altimeter responsive to the pressure of the atmosphere. meter will move the hand orf pointer H8 to a position on the dial which will indicate the apparent atmospheric pressure in terms of altitude or some other desired function.' At the same time the shaft 90 will move the dial ||6 in response to changes in the density of the atmosphere and thereby correct the reading of the pointer to give a corrected reading of absolute altitude, or other desired function.

In the application of the device illustrated in Fig. (i, the shaft 90 is connected with a pivoted hand or pointer |20 by a suitable operative connection, such as the rack |22 and pinion |24 The. instrument such as the altiso that the shaft 90 will move the pointer whenever the shaft moves in response to changes in f or other desired units toindicate at all times the current density of the atmosphere surrounding i the density responsive mechanism.

wmleltnere has been illustrated and desribed a suitable mechanical embodiment of the idea of theV invention and three' exemplary applications of the device', it is to be understood-What the invention is not limited to the construction so lllustrated and described but that such changes in the size, shape, and arrangement of parts may be resorted to as come within the scope oi' the subjoined claims.

Having now described the invention so that others skilled in the art may clearly understand tne same, what it is desired to secure by Letters Patent is as follows.

What is claimed is:

1. In a density responsive device, a movable element, power actuated means for moving said element, a sealed metallic bellows responsive to changes in the pressure of the surrounding medium for controlling said power actuated means, and a thermostat carried by said movable element and responsive to changes in the temperature of the surrounding medium for modifying the action of said bellows in controlling said power actuated means.

2. In a density responsive device, a movable element, power operated means for movingsaid element, a sealed metallic bellows responsive to changes in the pressure of the surrounding medium for controlling said power operated means, a device responsive to changes in the temperature of the surrounding medium for modifying Y the action'of said bellows in controlling said power operated means, and a connection between said temperature responsive device and said bellows effective to increase the modifying effects of said temperature responsive means on 'the action of said bellows as the pressure of the medium surrounding said bellows decreases.

3. .dnA air density responsive device comprislng, a sealed expansible bellows which tends to expand when subjected to an atmospheric presysure less than the pressure within said bellows, a springopposing expansion of said bellows, a movable support for said spring?, power` operated means for moving said support to vary'the force exerted by said spring, means actuated by initial expansion movements of said bellows to control said power actuated means, and temperatureesponsive/ means variably connected with said control nieans to modify the effect of said bellows thereon.

4. A density responsive mechanism comprising, an expansible bellows having a fixed end and a relatively free end which tends to move in response to changes in the density of the medium `surrounding said bellows, a spring opposing movement of said relatively free end, power operated means actuated'by initial movements of said relatively free end to change the loading'on said spring and restrain said relative free end of said bellows against movement beyond said initial movements effective to actuate said )spring loading device, and temperature responsive means operatively associatedv with said free end by a connection of variable mechanical advan age to modify the actuation of said power operated means by said bellows.

5. A/nair density responsive device comprisving, a sealed expansible bellows which tends Y' to expand when subjected 'to an` atmospheric pressure less than the pressure within said bellows, a

spring opposing expansion of' said bellows, a.

movable abutment for said spring, a hydraulic `piston for moving saidl abutment to vary the force exerted by said spring on said bellows, a,

with said bellows to exert a force thereon to modify the total force exerted thereon.

6. An air density responsive'device comprising, a sealed expansible bellows which tends to expand when subjected to an atmosphericl pressure less than the pressure within said bellows, a spring opposing expansion ofsaid bellows, a movable abutment for said spring, a` hydraulic piston for movingsaid abutment to vary the force exerted by said spring on said bellows, a valve for controlling the pressure of hydraulicfluid against said piston, means operatively connecting said bellows-with said valve, and temperature responsive means having a movable connection with said connecting means to modify the actuation of said valve by said bellows with increasing force as the pressure of the airsurrounding said bellows decreases.

7. An air density responsive device comprising, la sealed expansible bellows which tends to expand when subjected to an atmospheric pres sure less than the pressure within said bellows,

Aa spring opposing expansion of said bellows, a

movable abutment for said spring, a hydraulic piston for moving said abutment to vary the whereby said bellows will actuate saidvalve, and

a'temperature responsive device having a slidtain the volume of said bellows ksubstantially constant, temperature responsive means, a connectio-n of variable-mechanical advantage between said temperature responsive means andsaid bellows for modifying the actuationof said power operated means by said-bellows, a member connected to and movable with said vmovable abutment, a pointer operated by said member and a d ial associated with said pointernforindicating the density of the medium surrounding said bellows. r

9., In a density responsive device, a power actuatedVY movable element, a substantially constant volume pressure responsive device for controlling" the movements of said element to render said movements proportional to changes/in the pressure of the medium surrounding said device, .and temperature responsive means for modifying the controlling action of said pressure responsive vdevice with increasing eiect with increase in pressure'variations from a predetermined datum pressureJ to render said movements proportional to changes in the densityv of the surrounding medium;

l0. In a density responsive device, an element able connection with thel other arm of said bell which tends tochange its volume in response to changes in the pressure and temperature of the surrounding'medium, a movable abutment arranged toexert a force on said pressure responsive element to maintain its volume substantially constant,.and an element responsive t changes in the temperature of the surrounding medium for modifying the reaction between said pressure respons'ive element and said movable abutment only wherr'the gas pressure inside of said variable volume element differs from the pressure oi' the surroundingv atmosphere.

11. In a density responsive device, an element which tends to change` its volume in response to changes in the pressure and temperature of the surrounding medium, means resisting such change in volume, and means responsive to the temperalarranged to modify the tendency of said .ele-

ment to change its volume by a force proportionalto the temperature change and to the difference in density betweenthe inside and the outside of said variable volume element.

12. In a density responsive device, pressure responsive means for exerting a force proportional to `variations at a constant temperature in the pressure of the surrounding medium from a predetermined pressure, movable means for exerting a force in opposition to the force exerted by said pressure responsive means, and means for modifying the movements of said movable means by exerting a force proportional to variations in the temperature and pressure of the surrounding mendium from a predetermined temperature and pressure, said force assisting or opposed to the force of said movable means according to the character of the pressure or temperature variation.

13. In; a density responsive device, means for exerting a force in one direction varying withA changes in density due to changes in the temperature and/or pressure of the surrounding medium from predetermined values. of temperature and pressure, power actuated movable means for exerting a force in opposition to the force exerted by said tlrst mentioned means, an elastic/ connection vbetween said rst mentioned means and said movable means, and means for applying a corrective force to said rst mentioned means whenever there is a temperature change in said surrounding medium accompanied by a` diiference between the pressure of said medium and said predetermined 'pressure value.

14. 1n combination, a sealed bellows contaim,

ment, and a variable leverage mechanism between said temperature responsive element and said bellows.

15. -A density responsive device comprising an expansible chamber or lbellows subject to the temperature and pressure of the surrounding gas or atmosphere and sealed with a gas contained therein, and means, including 'a temperature responsive element, for, maintaining the density of the sealed gas constant, said means constructed and arranged to have deinite posi-A tions in accordance with the density ofthe surrounding gas, and means associated with the temperature responsive element to vary its effecaieasve tiveness constructed and arranged so that at a predetermined density of the surrounding gas the temperature responsive element will have no modifying eect but as the density changes from the predetermined value the modifying eects of the temperature responsive means increases.

16. A density responsive devicecomprising an expansible chamber orlbellows subject tothe temperature and pressure of the surrounding gas or atmosphere, which bellows requires a uniformly increasing force to maintain its volume constant as the density of the surrounding gas decreases at a constant temperature but which requires a uniiormly increasing additional force per degree increase in temperature to produce the same result under varying temperature conditions, means under control oi said bellows to maintainthe volume of said bellows substantially constant comprising means for applying a uniformly increasing force to said bellows as said density decreases, and means comprising a thermostatic element exerting a constant additional force per degree change in temperature and having a variable ratio lever connection withy said bellows for` increasing the reffectiveness of said additional force as the density decreases.

17. In a density responsive device, pressure and temperature responsive means for exerting a force when the density ofthe surrounding medium varies from a predetermined density, movable means for exerting a substantially equal force in opposition to the force exerted by said pressure responsive means, yand means for modifying the movements of said movable means by exerting a force tol assist or oppose the force of said movable means, said modifying means being operative to exert a 'force proportional to the variations in the temperature and pressure of the surrounding medium from a predetermined temperature and pressure.

18. In a density responsive device, means movable to definite positions corresponding to the density of the surrounding medium, means for causing movement of said movable means to a deiinite position corresponding to the existing density value comprising, means including a temperature responsive element and connections to restrain said movable means against movement from said position due to the eiect oi' temperature variations of the surrounding medium while said density remains constant but effective to cause movement of said movablemeans when the temperature variation is accompanied by a change in density.

19. In a device responsive to changes in'the weight per unit volume of the surrounding gas, having a body of confined gas maintained at substantially constant density, and lin which the ,pressure difference between the surrounding gas and the conned gas varies at a uniform rate with changes in density at a given temperaturek but at different uniform rates at other temperatures, a container for confining said conned gas a main means-forapplying a force to said container opposing and equal to the force created on said container by that part of said pressure dierence due to changes in density of the surrounding gas at said given temperature, and addinism including a temperature responsive elementfor applying force to said device to maintain its volume substantially constant, a connection, having a variable mechanical advantage,`between said temperature responsive element and said device, power operated means controlled by said expansible chamber device for varying said force and said mechanical advantage, said means havl0 ing the same position for any particular density regardless of temperature.

^ 21. A density responsive device comprising, an

in accordance with the density of the surround- 'ing'vmediumfor maintaining' the density of the sealed gas substantially constant, said means lin- 1 20 vcluding a thermostatic element operative to exert a. force on said container in response to changes in the temperature of said surrounding medium at densities other than said reference density.

25 22. In a device responsive-to changes in the weight per unit volume ci.' the surrounding gas, a body of coniined gas, the temperature of which remains substantially the same as the temperafined gas substantially constant during tempera ture changesby varying the pressure thereof com- 'prising, means controlled by changes in the pressure difference between' the pressure of the conned gas and the pressure of the surrounding gas forvarying the pressure of said confined gas, and additional means responsive to temperature changes-of said surrounding gas from a base temperature for increasing or decreasing the pressure of said confined gas', and mechanism responsive to changes in the density of the surrounding gas, from a base density, for causing said-temperature responsive means to increase or decrease the pressure' of saidconfined 

